Subject matter

Asphalt materials are widely used for paving and roofing applications using aggregates and bituminous binder, most likely from crude oil source. During the manufacturing of asphalt materials, elevated temperatures are required to ensure homogenous materials and ease of application. As organic-based material, the bituminous binder emits fumes and emissions, including Volatile Organic Components (VOC). Proper qualification and quantification of very small amounts of fume emissions from asphalt materials is gaining more and more interest today. However, there are various ways to define and quantify fume emissions from asphalt materials, but no standardised methodology has been established so far.
This TC aims to identify the most relevant methodology to assess fume emissions from asphalt materials, and to draft recommendations for fume emission evaluation. This is a new topic for the Rilem Cluster F that will increase interdisciplinary research and will thus bring additional value for the asphalt industry and researchers. Fume emissions evaluation will be considered at bituminous binder level, asphalt mixture level and in-situ level, considering different bituminous binders. Three task groups (TG) are foreseen: TG1 focuses on the binder level, TG2 on the mix level and TG3 on the in-situ level.
This TC will benefit from other TCs of Rilem Cluster F in terms of selection of the bituminous binders, as evaluated from TC 272 PIM, TC FBB, amongst others.

Terms of reference

The new TC will be active for 5 years. To achieve its goals, three task groups (TG) will be established, as indicated below. Final work programs of the TGs will be defined and proposed to the TC as soon as the TGs are established.
TG1 binder scale
This TG will focus on the evaluation of bituminous binder fume emissions at a laboratory scale. The initial task will consist of a literature review of the different laboratory methodologies used. Already some techniques are used such as Head Space analysis combining Gas Chromatography and Mass Spectrometry (GC-MS). Some other techniques have been also developed, which will be screened. Then, an inter-laboratory test program will be organised between participating laboratories with different methodologies and, if possible, a more profound study on a single methodology. The outcomes will help to identify precision and repeatability/reproducibility of different methodologies, and to select the most accurate one(s).
TG2 asphalt mixture scale
TG2 will aim to scale up fume emissions measurement from binder scale to asphalt mixture scale. Already at a laboratory scale, preparing hot mix asphalt generates fumes and emissions. However, the mixing process in a laboratory may differ from the plant mixing process also concerning emissions.
The aim of the TC will consist of a literature review and review of the different existing protocols for hot mix asphalt production, to identify the laboratory protocol simulating fume emissions most closely to fume emissions in asphalt mixing plant and application. Then an inter-laboratory test program will be set up between participating laboratories to evaluate different laboratory mixing protocols in view of fume emissions. Preferably, the same binders as in TG1 will be used. Thus, a correlation between the binder scale and mixture laboratory scale can be analysed.
TG3 construction site measurements
TG3 will assess fume emissions in full-scale production and application. First, existing protocols and equipment for in-situ fume measurements will be screened. Then, depending on the available options, one or two pavement construction jobsite(s) will be monitored and fume emissions analysed.
Already a positive and wide respond has been received from many RILEM members and beyond. The interested stakeholders are from academic, industry, equipment suppliers from Europe and America. Some are already RILEM members, others consider becoming new RILEM members.

Detailed working programme

The TC proposal was presented and discussed during the 2020 Annual Rilem Cluster F meeting. Based on the positive feedback and comments, the intended timeline is

• Spring 2021, confirmation of interest by the TAC;
• Until Summer 2021, call for participants and engaging interested stakeholders; nomination of TG leaders; drafting the TGs work programs more in detail; online meetings among interested parties;
• Fall 2021, meeting during the Annual Rilem Cluster F meeting to discuss with all Cluster F members;
• Spring 2022, official approval of the TAC (TC number);
• In 2022, a workshop will be organised bringing together experts and stakeholders, and to identify best approach to be considered;
• 2022 to 2024, inter-laboratory programs and initial communication of outcomes;
• 2025 formal communication of key findings through joint Rilem symposium with other TCs;
• 2027, State-Of-The-Art Report and Rilem recommendations.